Alkali metal alloy



atented Mar. 26, 1935 UNITED STATES ALKALI METAL ALLOY Dorothy Hall Brophy, Schenectady, N. 322, as-

signor to General Electric Company, a co ration of New York No Drawing. Application August 26, 1930, Serial No. 477,975

2 Claims.-

The present invention relates to alloys of alkali metals. More specifically this invention is concerned with a method of preparing such alloys and, particularly, a method of preparing caesium 5 alloys.

' due to its extreme reactivity in airdiificult to handle as such, It has been desirable to obtain it in a form wherein it is relatively more stable than in the metallic state and yet easily decomposable to said state when desired. For example, in introducing the element in tubes, such as photo-electric cells, difficulty has been encountered due to the fact that the cesium oxidizes so readily and forms a layer of oxide thereon before it can be introduced into the tube, and special devices have been resorted to for this purpose, such as the device shown in Letters Patent to Dorothy H. Brophy and William A. Ruggles, No. 1,685,666, dated September 25,

Metallic cesium is I have found that I cam prepare alloys'of cesium, the alloys being more stable and hence more easily handled than the metallic caesium itself, but, relatively speaking, sufliciently unstable in character so that the cesium may easily be obtained therefrom. Cesium alloys have not been prepared, as far as I am aware, direct from the metals because of the extreme reactivity of cesium in air. I have found that by employing certain precautions I can prepare cesium alloys direct from the metals.

For a consideration of what I believe to be novel and my invention, attention is directed to the following specification and the claims appended thereto. I

The cesium employed in making the alloys may be easily prepared by reduction of cesium chloride with metallic calcium in a vacuum. A method'which may be employed to obtain the cesium is disclosed in the Letters Patent above referred to. The metal is collected in a glass tube and covered with an oil such as a hydrocarbon oil or an organic liquid containing no hydroxyl group or groups which will react with cesium. An oil known to the trade as Nujol may conveniently be employed for this purpose. As soon as the metallic cesium is covered with oil it may be exposed to the air.

The glass tube containing the cesium immersed in a body of oil is heated to approximately 60 C. The temperature may be kept at 50 C.- C. The metals to be alloyed may now be added. This is preferably done by adding the metals in the 5 form of small pieces or shavings. The mixture is kept stirred and the caesium will be seen to change in color, becoming dark, and also becoming stiff and later breaking into fine particles.

The alloy which is formed is washed free of 10 the oil with a substance such as petroleum ether and then may be transferred to aluminum cylinders. While stored for future use, the alloy is covered with an inert medium, such as petroleum ether, carbon tetrachloride and the like.

Various metals have been found which alloy with cesium and give it up during vacuum distillation. As examples of such metals may be cited lead, tin, zinc, cadmium, silver, strontium, magnesium and barium. Alloys containing more 20 than one metal in addition to the cesium have also been prepared by the method of the present invention. As examples of these, barium-aluminum-cesium and strontium-aluminum-cesium alloys are mentioned.

While I have described my invention as applied to caesium, I wish it to be understood that similar metals may likewise be used to form alloys in the manner outlined. For example, in place of cesium, I may employ rubidium, potassium and 30 sodium. It will be understood that when such similar metals are employed the temperature of reaction will be different from that of cesium.

What I claim as new and desire to secure by Letters Patent of the United States, is:-

1. A method for preparing an alloy of cesium and a metal of the group consisting of lead, tin, zinc, cadmium, silver, strontium, magnesium and barium, which comprises contacting the cesium with one or more of said metals under an inert 40 medium at a temperature of 50 to 80 C. until the alloy is formed.

2. A relatively stable alloy of cesium and a metal of the group consisting of lead, tin, zinc,

cadmium, silver, strontium, magnesium and 45 barium, which alloy yields cesium on vacuum distillation.

' DOROTHY HALL BROPHY. 

